https://katlas.org/api.php?action=feedcontributions&feedformat=atom&user=TurionKnot Atlas - User contributions [en]2026-07-03T16:18:50ZUser contributionsMediaWiki 1.39.6https://katlas.org/index.php?title=Bugs&diff=1719461Bugs2013-04-25T15:49:12Z<p>Turion: </p>
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* The <code>PD</code> notation used by <code>KnotTheory`</code> is inadequate when a knot diagram contains kinks. For example, there is no way to tell the orientation of <code>PD[X[1,1,2,2]]</code>. You can define [[Braid_Representatives|braids]] with kinks, though: <code>Kink = BR[2, {1}]</code>. All knot invariants defined for braid representatives will be correctly evaluated. For example, the previously defined <code>Kink</code> will of course have the same invariants as the unknot. However, don't try to transform the braid into a planar diagram (<code>PD[BR[2, {1}]]</code>), as mathematica might hang up on that.<br />
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* Many knot invariants (including <code>Jones</code>) do not understand the (artificial but necessary) <code>PD</code> construct "<code>Loop</code>".<br />
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* Mathematica 9 defines its own tensor product, which causes bugs with the QuantumGroups` package. Stick with Mathematica 7 or 8 until Scott has it fixed.<br />
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* For some unexplicable bugs (in Mathematica 8 only?), it appears helpful to state the "context" explicitly, e.g. <code>KnotTheory`BR</code> instead of <code>BR</code>, or <code>MirrorTrefoil = PD[KnotTheory`X[1, 5, 2, 4], KnotTheory`X[3, 1, 4, 6], KnotTheory`X[5, 3, 6, 2]]</code> instead of <code>MirrorTrefoil = PD[X[1, 5, 2, 4], X[3, 1, 4, 6], X[5, 3, 6, 2]]</code>.</div>Turion